In those days, a commercial break on network television usually ran 60 seconds, in some cases 2 minutes, sometimes longer (though if the ad breaks were longer than 2 minutes, there was usually very few of them). Here, we have a 90 second commercial break.
This is part of a series of commercials called "Maisie & Jake". Maisie is a raisin, and Jake is a flake. They narrate a series of very short self-contained stories. This installment is called "The Sunken Treasure".
I like this series of this series of commercials....it's like a 90 second anthology series. It might be an interesting experiment to do this idea for YouTube, but without being a commercial.
SPOILER!! SPOILER!! A man searching for sunken treasure eventually finds it with the help of Post Raisin Bran.